This invention relates to a leg prosthesis device having an automatically locking and unlocking knee joint.
Heretofore, several attempts have been made to provide artificial limbs having joints which are automatically locked and unlocked while the wearer is walking. One of the problems encountered with such devices is to insure that the knee joint is positively locked in position when pressure is applied on the leg for supporting the wearer. However, it is necessary that the knee joint automatically unlock as the pressure is removed from the leg during walking so as to permit the wearer to walk in a normal gait. Providing a mechanism which will positively lock and unlock the knee joint without failure is a problem to which considerable attention must be given.
An example of an automatically knee locking device is disclosed in U.S. Pat. No. 2,071,711. In this particular device, it is alleged that the knee joint will be automatically locked in position as pressure is applied to the foot. When pressure is removed from the foot, a spring is utilized for disengaging a dog from the ratchet teeth so as to permit the knee joint to bend. While this particular prosthesis has never been seen by inventor, it would appear that there would be difficulty in controlling the degree of pressure required for locking and unlocking the knee joint during the walking operation.
Another artificial limb which incorporates a knee joint that is automatically locked and unlocked as pressure is applied during walking is disclosed in U.S. Pat. No. 2,943,622.